TABLE 1

Lung density measurements in RCT with augmentation therapy in AAT

First author [ref.]	Year	Patients randomised	Treatment and duration	Decline in lung density at TLC	Difference
Dirksen [13]	1999	28 AAT and 28 placebo	250 mg·kg⁻¹ AAT every 4 weeks for 3 years	Annual change: AAT −1.5 (sd 0.41) g·L⁻¹; placebo: −2.57 (sd 0.41) g·L⁻¹	1.07 (sd 0.58) g·L⁻¹ per year (p=0.07)
Dirksen [14]	2009	36 AAT and 35 placebo	60 mg·kg⁻¹ AAT every week for 2 years	Total change (2 years)^#: AAT −2.36– −3.38 g·L⁻¹; placebo −3.81– −4.82 g·L⁻¹	Total difference (2 years)^#: 1.47–1.59 g·L⁻¹ (p values between 0.084 and 0.049^#)
Stockley [18]	2010	Pooled analysis of previous RCTs. 60 AAT and 59 placebo	250 mg·kg⁻¹ or 60 mg·kg⁻¹ of AAT every 4 weeks or every week	Total change (2 years): AAT: −4.08 g·L⁻¹; placebo: −6.38 g·L⁻¹	Total difference (2 years): 2.29 g·L⁻¹ (p=0.006)
Chapman [15]	2015	93 AAT and 87 placebo	60 mg·kg⁻¹ of AAT every week for 2 years	Annual change: AAT −1.45 (se 0.23) g·L⁻¹; placebo −2.19 (se 0.25) g·L⁻¹	0.74 g·L⁻¹ (p=0.03)

^#According to the four different adjustments for evaluation of lung density performed in the study. TLC: total lung capacity; AAT: α₁-antitrypsin; RCT: randomised controlled trial; AT: augmentation therapy; sd: standard deviation; se: standard error.